1. Field of the Invention
The present invention relates to cross-linking agents and methods for preparing cross-linking agents. The present invention also relates to thermosetting resins and methods of preparing thermosetting resins. The present invention further relates to articles with a coating layer and methods of preparing an article with a coating layer.
2. Discussion of the Background
Blocked polyisocyanates and the use thereof in thermosetting one-component polyurethane systems are known. They impart to top clear coats significantly better resistance to environmental influences, especially acid rain, than is the case in systems comprising cross-linking aminoplastic resins. Among other applications, blocked polyisocyanates are also used proportionally in combination with aminoplastic resins as cross-linking components in “hybrid systems.” Blocked polyisocyanates also have considerable importance in the field of thermosetting powder lacquers.
Polyisocyanates modified with secondary aminosilanes are also known. For example, aminopropyltrialkoxysilanes modified with maleic or fumaric acid esters may be reacted with isocyanates in order to achieve better adhesion with less CO2 evolution than is the case with sealing compounds based on pure isocyanate prepolymers (see European Patent No. 596360 and U.S. Pat. No. 6,005,047). Structurally related adducts are also used as a hardener component in aqueous 2-component PUR lacquers (see European Patent Nos. 872499 and 949284).